Cantor's primary, though, provided the final push that likely will doom any chance immigration reform had this year — and possibly into the future. Dave Brat, the unknown college professor who beat Cantor, the No. 2 Republican in the House, made immigration a central issue of the campaign. He even pushed Cantor to the right on the issue leading to the House Majority Leader sening out mailers that boasted he blocked "amnesty" in Congress.

"Immigration is the superficial issue," Erick Erickson, the editor of the conservative website RedState, told Business Insider. "But underneath there is a lot of bad blood with conservatives who feel like [Cantor] has repeatedly made them promises and betrayed them; constituent services that were run for Washington lobbyists, not actual citizens of the district; a very heavy-handed staff that was hard for constituents to deal with and for conservatives to reason with; and he took his eye off the prize. He was looking at the Speaker's chair, not his own."

Though he cast immigration as a more surface-level problem for Cantor, Erickson noted the issue still provided a foundation for Brat's victory.

"But immigration was the issue on which the race could be built," said Erickson. "If we couldn't trust Cantor on a long list of broken promises and half-hearted deals, we couldn't trust him on immigration."

Some Democrats disputed immigration reform was on its death bed prior to Cantor's loss, saying House Speaker John Boehner would be the one to determine its fate. Boehner's office said it had no comment on Cantor's loss Tuesday night. White House aide Dan Pfeiffer and others made the point that on the same night Cantor lost, U.S. Sen Lindsey Graham (R-South Carolina) — a sponsor of the Senate's immigration bill — resoundingly won his primary.

"Immigration reform has been held hostage by Speaker Boehner. It's up to him," one senior Senate Democratic aide said.

The aide also identified Cantor's handling of local party elections as a potential source of anger towards him inside his district.

"I'd just point out that the way Cantor and his operatives engaged in an iron-fisted slating process outraged local conservatives," the aide said. "There was a lot of anger about his style and tactics."

Other Democrats, however, were more pessimistic about the imminent future of immigration reform. Still, they said Cantor's loss squeezes Republicans and puts the party in a nationally uncomfortable position ahead of the next two election cycles — especially the presidential campaign in 2016. A poll released Tuesday showed more than six in 10 voters nationally support immigration reform that includes a path to citizenship for people in the country illegally.

"It puts Congressional Republicans in a very difficult bind: risk losing primaries, or risk losing national elections to Democrats for the next generation," Tom Jensen, the director of Public Policy Polling, told Business Insider.

Jensen cast congressional primary victories like Brat's as a Pyrrhic victory for immigration reform opponents that might yield short-term wins but would keep conservatives far from the White House.

"Immigration reform isn’t going away, and if the Republicans continue to block it, Democrats will keep getting 70% plus of the Hispanic vote. It’s very hard for the GOP to win a Presidential election if that continues," explained Jensen. "Enough Republicans are going to have to just take the risk of primary backlash by voting for this to get it passed, or else the party will continue paying the price in November for years to come."